Cutter head for a bark removing machine

ABSTRACT

A cutter head for a hole-rotor type barking machine. The cutter head comprises a plane ring disc provided with a number of mutually spaced cutter blades projecting from the disc. Each cutter blade is provided with a guiding element forming a support surface. The support surfaces of the guiding elements form a conical surface coaxial with the ring disc. Each guiding element is supported by the ring disc along the entire length of the element and is preferably cut from a ring shaped blank of solid material.

att 1 1 Get. 22, 1974 CUTTER HEAD FOR A BARK REMOVING MACHINE Inventor:Antti Tapani Valo, 08100 Lohja 10,

Finland Filed: Mar. 6, 1973 Appl. No.: 338,498

Foreign Application Priority Data Mar. 9, 1972 Finland 629/72 11.8. C1.144/218, 144/162 R, 144/176, 144/208 E, 144/220 lnt. Cl. B27g 113/00Field of Search 144/208 R, 208 E, 218, 144/220, 162, 176, 4

References Cited UNITED STATES PATENTS 8/1969 Wexell 144/162 R 3,542,30211/1970 Salzmann, Jr 144/176 X Primary ExaminerAndrew R. JuhaszAssistant Examiner-W. D. Bray Attorney, Agent, or F irmLadas, Parry, VonGehr, Goldsmith & Deschamps 5 7 1 ABSTRACT A cutter head for ahole-rotor type barking machine. The cutter head comprises a plane ringdisc provided with a number of mutually spaced cutter blades projectingfrom the disc. Each cutter blade is provided with a guiding elementforming a support surface. The support surfaces of the guiding elementsform a conical surface coaxial with the ring disc. Each guiding elementis supported by the ring disc along the entire length of the element andis preferably cut from a ring shaped blank of solid material.

6 Claims, 5 Drawing Figures CUTTER HEAD FOR A BARK REMOVING MACHINE Thepresent invention relates to a cutter head for a bark removing machineincluding a ring-shaped holerotor through which logs to be debarked arepassed longitudinally, the cutter head comprising a plane ringshapedsupporting disc to be fastened at the input side of the rotor andprovided with at least one, preferably several mutually spaced cutterblades projecting from the disc and each provided with a support surfaceassociated with the blade.

In order to cut off the lower end swelling, other excessively thicksections, knot projections and equivalent portions of the logs to be fedthrough the hole rotor of a bark removing machine before the barkingblades proper, it is a known procedure to provide the hole rotor of thebark removing machine with a cutter head which is provided with severalcutter blades distributed evenly around the circumference.

In accordance with a known construction, the cutter head comprises aplane ring disc which is fastened to the hole rotor and locatedsubstantially perpendicularly to the axis of rotation of the hole rotorand to which the cutter blades are fastened each of them separately soas to project from the plane of the ring disc. Since the mesh angle ofthe shearing edge of the cutter blades must be positive in order toproduce chips, the cutter blades, however, tend to penetrate into thewood and thereby to drive the log through the hole rotor at a ratehigher than the rate of feeding at which the barking blades proper havebeen meant to work. This of course deteriorates the bark removing resultand subjects the cutter blades to high strains.

Another type of a cutter head is also previously known, in which thereis a ring disc expanding like a funnel, which ring disc itself supportsthe cutter blades. Besides the above drawbacks, such a construction alsohas the disadvantage that the funnel shaped ring disc allows a verynarrow space for the chips removed by the cutter blades in between thering disc and the log, through which space the chips must leave thecutter head. It is clear that the risk of blockage of such a cutter headis remarkable.

There is also previously known a chipper in which to a solid rotatablesupporting disc is fastened a plurality of radial cutter blades aroundthe axis of rotation of the supporting disc. Each blade is provided witha wing-like guide plate mounted after the blade with respect to thedirection of rotation and located apart from the supporting disc, sothat a space is formed between the guide plate and the supporting disc.The purpose of the guide plate is to prevent the blades from cutting toodeep into the wood. Each guide plate is located substantially at rightangles to the axis of rotation and the thickness of the guide platedecreases towards the rear edge, which is spaced from the subsequentblade, so that a radial slit for removing of the chips is formed betweensaid rear edge and said subsequent cutter blade.

A disadvantage of the construction of the type described is that for thecutter heads, which, it is true, have the same diameter but which havedifferent numbers of cutter blades, there has to be made a guide plate,which with respect to its construction and form is accurately designedespecially for this number of cutter blades. As the guide plate projectsfreely'from the corresponding blade, each guide plate with bladesbecomes rather weak and light, which is of disadvantage in a cutterhead.

A purpose of the present invention is to provide a construction that isnot accompanied by the above drawbacks, and this is achieved by means ofa cutter head in accordance with the invention, which is characterizedin that the cutter head comprises separate, mutually spaced guidingelements fastened to the plane ring-shaped supporting disc and formingseparate support surfaces located on a conical surface and facing theapproaching log to be machined, said guiding elements further beingseparated from each other by slits in which said cutter blades aremounted and through which the chips are removed.

According to the invention there is provided a cutter head, in which theguiding elements are supported over their whole length by the supportingdisc and the guiding elements can simply be cut off from a ring-shapedblank to an arcuate element of a length depending of the desired numberof cutter blades in the cutter head. By forming the guiding elementssolid the cutter head will get enough of weight to be able to performthe cutting action without it being necessary to fasten separate extraweights on to the cutter head or the rotor. The guiding element and thecutter blade holder can also be made in one piece.

The invention will be described more in detail below with reference tothe attached drawings, wherein FIG. 1 shows a perspective view, partlyin section, of a first embodiment of a cutter head in accordance withthe invention,

FIG. 2 shows a portion of the cutter head as viewed in the direction ofthe arrows IIII shown in FIG. 1,

FIG. 3 shows another embodiment of the cutter head in a way similar tothat of FIG. 1,

FIG. 4 axially from the front shows a ring-shaped blank for the guidingelements,

FIG. 5 shows an axial section of the blank according to FIG. 4.

The cutter head ll shown in the drawings is designed so as to befastened to the hole rotor 2, shown in broken lines, of the barkremoving machine on its input side in respect of the direction of inputA of the log to be barked. The cutter head comprises a plane ring disc 3which supports several cutter blades 4.. Each cutter blade comprises ablade holder 5 fastened to the ring disc 3, to the groove 6 of whichholder the blade proper 7 can be fastened so that the shearing edge 8.of the blade forms an angle a with respect of the plane of the ring disc(FIG. 1). The purpose of the angular position of the shearing edge 8 ofblades 4 is to trim down the thick sections knot projections etc.referred to above by cutting chips therefrom at an angle to wood fiberdirection, and thus prepare the periphery of the log for the maindebarking operation. I

The cutter head 1 moreover includes for each cutter blade, a disc-likeguiding element 9 following the blade in respect of the direction B ofrotation, which constitutes a curved support surface 10, which isarranged at angle B in relation to the ring disc plane, substantiallyequal to the angle a formed by the shearing edge 8 of the blade. Betweenthe support surface 10 and the shearing edge 8 there is, however, in theaxial direction, a difference in elevation 11, which differencecorresponds to the length of the chip removed by the cutter head.

In the embodiment shown in FIGS. 1 and 2 the guiding element 9 isprovided with an edge flange 12, and an end flange 15, by means of whichthe guiding element is fastened to the plane ring disc 3. In thisembodiment the guiding element is not at all in contact with the cutterblade, but there is a space 13 between them, and in the direction ofrotation the guide wing does not extend until the next cutter blade butthere is a slit 14 between them.

In the embodiment shown in FIG. 3 the cutter head 16 is provided with asomewhat different guiding element 17, which also comprises a curvedsupport surface 18 but which is made of a solid material over its wholelength. The guiding element is provided with a cutter blade holder 19for a cutter blade 20.

When the log is being fed through the rotating rotor and when the cutterblades are cutting excessively thick portions of the log, the log is allthe time being pressed against the support surface of the guidingelements so that the log cannot rush forward but proceeds under fullcontroll and evenly at the rate of cutting of the blades through therotor. The chips removed by the cutter blades are admitted through theslits 14 between the blades and the guiding elements to be thrown out ofthe cutter head.

In the case of a cutter head that has only one cutter blade, the guidingelement forms an almost complete circle, however, leaving again a slit14 between the end of the wing and the blade.

The blade 7 (FIG. 2) of the cutter blade, can be adjusted in its grooveby means of adjusting screws 21 so that the difference in elevation ofthe shearing edge of the blade in relation to the support surface of theguiding element can be adjusted to the desired level in connection withgrinding of the blade or with changing of the length of the chip.

In FIGS. 4 and is shown a ring-shaped blank of a solid material, fromwhich guiding elements 17 of desired length can be cut off, as is shownwith broken lines. Also the guiding element 9 can be cut off from aring-shaped blank of suitable cross section.

The drawings and the related description are only intended to illustratethe idea of the invention. In its details the cutter head may show evenconsiderable variability within the scope of the patent claims.

What I claim is:

1. A cutter head for a bark removing machine having a ring-shapedhole-rotor through which logs to be debarked are passed longitudinally,the cutter head comprising a plane ring-shaped supporting disc to befastened at the input side of the rotor and provided with at least oneand preferably several mutually spaced cutter blades projecting from thedisc, each being provided with a support surface associated with theblade, characterized in that the cutter head comprises separate,mutually spaced guiding elements fastened to the plane ring-shapedsupporting disc and forming separate support surfaces located on aconical surface and facing the approaching log to be debarked, saidguiding elements further being separated from each other by slits inwhich said cutter blades are mounted and through which the chips areremoved.

2. A cutter head in accordance with claim 1, characterized in that eachguiding element, at least with respect to the direction of rotation, isfastened at its rear edge by means of an end flange and at its innercircumferential edge by means of an edge flange to said ringshapedsupporting disc.

3. A cutter head in accordance with claim 1, characterized in that saidguiding elements are formed of a solid material.

4. A cutter head in accordance with claim 3, characterized in that saidguiding elements are cut off from a ring-shaped blank.

5. A cutter head in accordance with claim 1, characterized in that aspace is formed between the guiding element and the corresponding cutterblade.

6. A cutter blade in accordance with claim 1, characterized in that theguiding element is provided with a cutter blade holder for a cutterblade, the position of the shearing edge of which is adjustable inrelation to the support surface of the guiding element.

1. A cutter head for a bark removing machine having a ringshapedhole-rotor through which logs to be debarked are passed longitudinally,the cutter head comprising a plane ring-shaped supporting disc to befastened at the input side of the rotor and provided with at least oneand preferably several mutually spaced cutter blades projecting from thedisc, each being provided with a support surface associated with theblade, characterized in that the cutter head comprises separate,mutually spaced guiding elements fastened to the plane ring-shapedsupporting disc and forming separate support surfaces located on aconical surface and facing the approaching log to be debarked, saidguiding elements further being separated from each other by slits inwhich said cutter blades are mounted and through which the chips areremoved.
 2. A cutter head in accordance with claim 1, characterized inthat each guiding element, at least with respect to the direction ofrotation, is fastened at its rear edge by means of an end flange and atits inner circumferential edge by means of an edge flange to saidring-shaped supporting disc.
 3. A cutter head in accordance with claim1, characterized in that said guiding elements are formed of a solidmaterial.
 4. A cutter head in accordance with claim 3, characterized inthat said guiding elements are cut off from a ring-shaped blank.
 5. Acutter head in accordance with claim 1, characterized in that a space isformed between the guiding element and the corresponding cutter blade.6. A cutter blade in accordance with claim 1, characterized in that theguiding element is provided with a cutter blade holder for a cutterblade, the position of the shearing edge of which is adjustable inrelation to the support surface of the guiding element.